Deperecate (and remove) org.eclipse.equinox.concurrent

[laeubi]

It was added as part of Bug 253777 but seems to not gather any wider adoption and likely obsolete these days with Java 8 CompletableFuture.

The only reference I could find is ECF on one place but nowhere else in any platform code.

Also on maven I do not see any references:

• https://mvnrepository.com/artifact/org.eclipse.platform/org.eclipse.equinox.concurrent

So my proposal would be:

1. Deprecate the bundle
2. Remove it on next release
3. Who even wants to still use it can do so by reference an older release or maven coordinate.

@tjwatson or others any concerns?

[tjwatson]

I have proposed removing this in the past but was met with some resistance from the ECF folks. But given we have had no development on this bundle in years I think it is fine to stop building it. Existing users can just use the existing releases out there.

[merks]

A problem here is that the Platform depends on ECF so this will just continue to be dragged in if ECF keeps using it. So a PR to remove it from ECF would be good. Then I really need to start asking some hard questions about where ECF is headed? Do they actually merge PRs and do they plan to produce timing releases? A PR to remove this dependency would help provide some additional fuel for that conversation. So I'm not saying we should do this, I'm just pointing out that in the current state, removing it won't remove it.

[laeubi]

A problem here is that the Platform depends on ECF so this will just continue to be dragged in if ECF keeps using it. So a PR to remove it from ECF would be good.

I don't think its a problem per se, it will just become a random third party dependency like guava or what else... of course if ECF has strong needs for this it could decide to simply adopt the code and do whatever it likes.

I just try to find out if we can go forward with getting rid of some things directly in Equinox... let it be delete stuff or move it right/left to someone still interested.